1. Field of the Invention
The present invention relates to the fabrication of semiconductor electronic components, and in particular, to the fabrication of waveguides or optical conductive structures on a semiconductor device and to the integration of the fabrication of the optical conductor with the fabrication of the copper conductor in the semiconductor device.
2. Description of Related Art
Electronic devices having both an optical conductor pathway and a copper conductor pathway are of increasing importance in the electronic industry since both light and electricity can be used together to provide enhanced functions for the electronic device. The fabrication of copper conductors on a semiconductor device is well known in the art and basically comprises forming a trench or opening in a dielectric and filling the trench with copper metal.
With regard to the optical conductor in the electronic device, they are usually constructed as planar waveguide films for guiding light in the electronic component. The waveguides are typically used as directional couplers, filters, switches and optical interconnections for electronic circuits. In general, a waveguide comprises a first layer of material such as silicon dioxide (SiO2), an intermediate layer of a material which has a lower refractive index than that of the SiO2 followed by a top layer of the first layer SiO2 material. In these type waveguides, optical power is confined to the lower index layer by the standard process of total internal reflection at the interface between the two layers.
The efficient and cost effective fabrication of electronic devices containing both optical conductor structures and copper or metal conductor structures using conventional processes is also highly desirable in the electronic component fabrication industry.
Bearing in mind the problems and deficiencies of the prior art, it is therefore an object of the present invention to provide a method for making an optical waveguide in an electronic component containing copper conductors such as a semiconductor device.
It is another object of the present invention to provide a method for making an optical waveguide in an electronic component wherein the electronic component has trenches containing copper conductors some of which copper conductor trenches are to be replaced and fabricated for use as a waveguide.
A further object of the invention is to provide a method for making copper conductor structures in an electronic component containing optical waveguide structures using some of the waveguide trenches as a copper containing trench.
Another object is to provide an optical waveguide transmission system integrated with a semiconductor device made using the method of the invention.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The above and other objects and advantages, which will be apparent to one of skill in the art, are achieved in the present invention which is directed to, in a first aspect, to a method for making an optical structure waveguide in an electronic component comprising the steps of:
forming a trench or other opening in a dielectric layer;
depositing a first conformal layer of SiOxNyHz or other dielectric material having a first index of refraction and preferably graded from an index refraction higher at the beginning of the deposition to a lower index at the end of the deposition such as 2.0 to 1.46;
depositing on the first conformal layer a second core conformal layer of SiO2 or other dielectric material having a second index of refraction substantially equal to the low index of refraction of the first graded conformal layer;
etching the second core conformal layer to a desired embedded vertical thickness in the trench in the form of a rectangle the etch embedded layer being bounded on the bottom and sidewalls by the first conformal layer;
depositing on the etched substrate a third conformal layer of SiOxNyHz or other dielectric material having a third index of refraction higher than the second index of refraction and preferably graded from a low index of refraction at the beginning of the deposition substantially equal to the index of refraction of the second index of refraction of the third conformal layer to a high index at the end of the deposition; and
planarizing the dielectric layer until the first and third conformal layers are planar at the surface of the dielectric with the second core conformal layer in the trench being surrounded at the bottom and side faces thereof by the first conformal layer and on the top by the third conformal layer.
In another aspect, the present invention relates to a method for making an optical waveguide structure in an electronic component containing copper conductor structures comprising the steps of:
fabricating copper conductor structures in a dielectric layer with the copper layer being planar with the dielectric layer;
depositing a conformal protective layer such as SiNxHy over the device and the copper conductor structures;
depositing a masking layer on the protective layer;
defining a portion of the masking layer to contain an optical waveguide structure in the dielectric layer;
etching the masking layer exposing the protective layer;
etching the protective layer and dielectric layer to the desired trench depth; and
forming the optical waveguide structure as described above.
In another aspect of the invention a method is provided for making copper conductor structures in openings containing waveguide structures in an electronic component containing optical waveguide structures comprising the steps of:
forming openings in a dielectric layer;
forming optical waveguide structures in the openings;
depositing a masking layer on the dielectric layer and optical waveguide structure;
defining a portion of the masking layer where a copper conductor structure is desired to be formed in place of the waveguide structure;
etching the waveguide structure;
stripping the mask;
depositing barrier material and copper in the trench; and
planarizing the electronic component by chemical-mechanical polishing or other planarizing means to form a planar waveguide structure and copper conductor surface.
In a further aspect, the present invention relates to a method for raking an optical waveguide structure in a copper containing trench in an electronic component having a plurality of copper containing trenches comprising the steps of:
forming an electronic component having a plurality of copper containing trenches;
depositing a conformal protective layer over the substrate surface;
depositing a mask on top of the protective layer;
defining and etching the mask at a copper containing trench where an optical waveguide is desired;
etching the copper from the trench; and
forming the waveguide in the etched trench as described above.
In another aspect of the invention an optical waveguide transmission system integrated with a semiconductor device is provided comprising:
a dielectric having a trench therein;
an optical conductor in the trench, having a second index of refraction, said conductor having a substantially rectangular cross-section; and
an encapsulating optical medium in the trench surrounding the optical conductor having a first index of refraction higher than the second index of refraction.
The optical waveguide transmission system is formed in a trench or opening in a dielectric layer of an electronic component.